START WITH THE ‘QUICK WINS’

THEY IMPROVE ENERGY EFFICIENCY WITHOUT REQUIRING SIGNIFICANT INVESTMENT

Sitting down with Turbomachinery International at PowerGen Europe, in June, Dr. Werner Janik, ABB’s global head of sales for Energy Efficiency and Service in Power Generation, proclaimed his hobby to be energy efficiency.

“When people invest in a new plant,” said Janik, “their concern is primarily to keep the total installed cost as low as possible. Energy efficiency becomes a relevant topic after a couple of years when they realize they can do more with their existing assets, or when political and economic pressure rises to produce more output while reducing energy consumption and emissions.”

To help older facilities, his company recently launched an energy efficiency initiative wherein power plant operators have their facilities evaluated so they can best decide what to do. This week-long evaluation results in an energy savings report which prioritizes improvement opportunities.

For example, in May 2012, at the Jaworzno III Power Plant in Jaworzno, Poland, an evaluation predicted annual energy savings at Unit 4 in the range of 125,000 MWh thermal and 21,000 MWh electrical, a gross savings of almost $3 million per year. Some 43 energy savings opportunities were identified for the power plant’s turbine island, boiler island, generator, electrical balance of plant, materials handling, and motors & drives. Fifteen of these projects were designated as “quick wins.”

“Quick wins are important because they can improve efficiency without requiring any significant investment,” said Janik. He cited a case in which a plant needed to feed make-up water into its water-steam cycle at a rate of 10% of its water circulation (water replacement is normally in the 3% to 7% area).

“The cost of this lost water was about $1 million per year,” said Janik. “The solution was easy: Find the leak.”

On average, roughly one third of opportunities are quick wins that can save millions of dollars. In addition there are often several smaller projects in the $2,000 to $300,000 range that can offer payback in about 1.5 to 3.5 years, said Janik. “Even in a welloperated plant, there are typically 30 to 50 opportunities. One third of these are small opportunities, the rest are medium-to-large.”

The average volume of potential projects in a coal-fired power station could cost from $2 million to $4 million to correct, according to ABB estimates. For smaller applications, such as wasteto- energy plants, the cost could be about $1 million. By implementing the measures resulting from the energy assessment efficiency can be improved anywhere between 5% and 10%.

An evaluation of the Al Taweelah Combined Cycle Gas Turbine Desalination Plant in the United Arab Emirates uncovered energy savings (excluding large capital investment opportunities) in the range of 380,000 MWh thermal and 70,000 MWh electrical. Annual gross savings were estimated at up to $10 million. Some 32 opportunities were identified in areas such as gas turbine, HRSG, steam turbine, desalination, and motors & drives. Gas turbine energy efficiency opportunities included the following:

1. Quick win: Optimization of the evaporative cooler operation may reduce net plant heat rate with no investment cost. Water distillate consumption would decrease by more than 16,000 m3/year (savings of $229,500/year).

2. Medium investment: Replace course filters with new ones if investigation indicates their degraded condition leads to excessive pressure drop on pulse air filters. Capacity increase of up to 0.6 MWe per unit (Savings of $527,000/year).

3. Increasing the fuel gas supply temperature (up to 200ºC) with recovered heat reduces the fuel consumption since the sensible heat of the fuel increases. Limiting factors are the existing GT fuel nozzles (which may require modification or replacement) and potential modification to the fuel gas skid and balance of plant. Investment cost from low to high, depending on the GT impact (fuel savings: $1,700,000/year).

ABB provides a chart that indicates the complexity of the project, the rough amount of investment and energy savings (Figure 1). “Complex projects give the best energy savings and have the longest payback period,” said Janik. “Small projects have a quick payback. It is best to combine a series of small projects and a few larger projects to achieve a sustainable efficiency improvement.”